M. Night Shyamalan's latest non-happening will prove a litmus test of Will Smith's continued drawing power.

The last time M. Night Shyamalan tried his hand at a big-budget “Man vs. Wild” episode, with 2008’s “The Happening,” the unseen villainess was none other than Mother Nature herself. In the decided non-happening that is Shyamalan’s latest, “After Earth,” the threats lurking on a post-apocalyptic blue planet include baboons, predatory birds and a giant alien beastie that looks like a rejected prototype from H.R. Giger’s workshop. (At least there are no Tom Cruise clones.) But it’s Shyamalan’s career, and that of producer-director Will Smith, that seem to be struggling for survival in this listless sci-fi wilderness adventure — a grim hodgepodge of “Avatar,” “The Hunger Games” and “Life of Pi” that won’t come anywhere near equaling those juggernauts with the ticketbuying public. Opening in a very crowded summer frame, the pic will prove an even greater litmus test of Smith’s continued drawing power than 2008’s ill-conceived Christ allegory “Seven Pounds.”

Clearly envisioned as a franchise starter for Smith and Sony, “After Earth” comes with a detailed press kit offering pages and pages of backstory fleshing out the film’s futuristic universe, little if any of it actually addressed in the pic itself (suggesting either long-range sequel plans or lots of carnage on the cutting-room floor). Smith, who gave one of his best performances in the similar last-man-on-Earth vehicle “I Am Legend,” here mostly takes a backseat to his 14-year-old son, Jaden, whose Kitai Raige (how’s that for a character name?) is a cadet in the United Ranger Corps, a militia formed a millennium ago when Earth was in the last stages of its man-made downfall (cue montage of floods, fires, riots). Now, humankind has a new home planet, Nova Prime. The only problem: a hostile alien species that considers Nova Prime its birthright, and has spent most of the past thousand years trying to kill us with genetically engineered monsters known as ursas.

Some time before our story begins, one such ursa has made lunch out of Kitai’s older sister, Senshi (Zoe Isabella Kravitz), an incident that has driven an emotional wedge between Kitai and his father, Cypher (the elder Smith), each of whom on some level blames the other for the loss. Making matters worse, Cypher is something like the George Patton of the Ranger Corps, storied for slaying ursas with his patented “ghosting” technique, in which he becomes invisible to the scent-guided creatures by suppressing his pheromone-generating fears. (There is no simple explanation for anything in this movie.) In short: It’s a tough act for young Kitai to live up to.

In a bid to get this slow-moving story started with a bang, Shyamalan opens with the spaceship crash that eventually strands Kitai and Cypher on Earth, then flashes back 72 hours to pile on yet more backstory. Kitai has failed, it seems, to advance to the next level in Ranger training, putting a damper on his reunion with Dad, who’s just returned from his latest mission. But as wise old Mom (Sophie Okonedo) advises Cypher, Kitai “doesn’t need a commanding officer, he needs a father.” So when it’s time for Cypher to ship out again, he brings his son along for the ride, little realizing that an asteroid storm will tear their ship to smithereens and leave them the only two human survivors. There’s also one non-human survivor: a captured ursa that the ship was transporting to use in a training exercise, now loosed from its cage and prowling the Earth.

Laid low with a badly broken leg and jacked up on hallucinogenic painkillers, Cypher spends most of the rest of the film doing one long “Camille” routine, while Kitai begins the more-than-60-mile trek to the other half of the ship’s wreckage, to retrieve a much-needed emergency beacon. It’s a journey in which a lot of the rules seem rather arbitrary: For reasons never satisfyingly explained, the Earth’s atmosphere has become too toxic for human consumption, but poses no threat to other oxygen-breathing fauna that seem to have flourished in mankind’s absence. At the same time, the planet’s surface temperature has evidently been ravaged by climate change, forcing Kitai to get to certain designated “hot spots” by nightfall in order to avoid turning into a human popsicle.

Papa Smith, who also takes a story credit, reportedly conceived of “After Earth” as a contemporary survival tale set in the wilds of Alaska, and the pic might have packed more punch rendered in spare, Jack London-esque fashion. Festooned instead with special effects— from CG animals (none as convincing as “Pi’s” tiger) to bits of CG volcanic ash hovering against charcoal CG skies — it’s a leaden affair, even at barely 90 minutes (not counting credits). Donning an impermeable tough-guy facade, and hovering on the edge of consciousness for much of the running time, the senior Smith gives one of the least substantive performances of his career, while the undeniably charismatic Jaden toggles between two primary modes of expression: paralyzing fear and simmering rage.

Though he shares screenplay credit with Gary Whitta, Shyamalan is clearly a director-for-hire here, his disinterest palpable from first frame to last. Nowhere in evidence is the gifted “Sixth Sense” director who once brought intricately crafted setpieces and cinematic sleight-of-hand to even the least of his own movies. This film, rather, is essentially one long anticlimax culminating in the inevitable duel between Kitai and the amorphous-looking ursa — a creature as shapeless and indistinct as “After Earth” itself.

Shot by frequent David Cronenberg cameraman Peter Suschitzky on Sony’s new F65 CineAlta digital system, the pic sports a crisp but generally undistinguished look, with a muted color palette and much obvious post-production image manipulation. Production designer Tom Sanders and costume designer Amy Westcott offer a fairly rote vision of the future in steely modernist architecture and earth-toned unitards.